Exercises 1–3
1. for each of the following study descriptions, identify whether the study is a survey, an observational study, or an experiment, and give a reason for your answer. for observational
studies, identify the population of interest. for experiments, identify the treatment and response variables.
a. a study investigated whether boys are quicker at learning video games than girls. twenty randomly selected boys and twenty randomly selected girls played a video game that they
had never played before. the time it took them to reach a certain level of expertise was recorded.
b. as your statistics project, you collect data by posting five questions on poster board around your classroom and recording how your classmates respond to them.
c. a professional sports team traded its best player. the local television station wanted to find out what the fans thought of the trade. at the beginning of the evening news program, they
asked viewers to call one number if they favored the trade and a different number if they were opposed to the trade. at the end of the news program, they announced that 53.7% of callers
favored the trade.
d. the local department of transportation is responsible for maintaining lane and edge lines on its paved roads. there are two new paint products on the market. twenty comparable
stretches of road are identified. paint a is randomly assigned to ten of the stretches of road and paint b to the other ten. the department finds that paint b lasts longer.
e. the national highway traffic safety administration conducts annual studies on drivers’ seatbelt use at a random selection of roadway sites in each state in the united states.
f. people should brush their teeth at least twice a day for at least two to three minutes with each brushing. for a statistics class project, you ask a random number of students at your
school questions concerning their tooth brushing activities. to determine if seatbelt usage has increased, data are analyzed over two successive years.
g. a study determines whether taking aspirin regularly to prevent heart attacks. a large group of male physicians of comparable health were randomly assigned equally to taking
an aspirin every second day or to taking a placebo. after several years, the proportion of the study participants who had suffered heart attacks in each group was compared.